Conformationally restricted congeners of the opiate agonist 5-m-hydroxyphenyl-2-methylmorphan were prepared as probes to examined topological requirements for in vitro binding to opiate receptor subpopulations. One congener was inactive in vivo as an agonist or antagonist and did not bind appreciably to opiate receptor preparations. A second congener was a weak antagonist with no agonist properties and had a weak binding constant for opiate receptors. Work is presently progressing on the synthesis and biological evaluation of further members of this series.